Skip the auto shop - Our mechanics make house calls

How Do Drive and Serpentine Belts Work?

serpentine belt

The drive belt on your vehicle delivers power to the car’s engine, alternator, water pump, power steering pump, and air conditioner compressor. Usually, a car has one or two drive belts, and if there is only one, it is often referred to as a serpentine belt.

The drive belt is constructed from sturdy rubber, but eventually, it will sustain some wear. You can usually expect it to last up to 75,000 miles, but most mechanics recommend replacing it at the 45,000 mile mark, because if it breaks, you won’t be able to drive your car. And if the engine runs without a belt, your coolant won’t circulate, and your engine could overheat.

How do you know if the belt needs to be replaced?

You’ll probably notice chirping or squeaking sounds. If you do, you have your mechanic examine the belt. Splits, cracks, missing chunks, damaged edges, and glazing are all indications of excessive drive belt wear, and the belt should be replaced. You should also have the drive or serpentine belt replaced if it has become soaked in oil – it might not cause a problem right away, but oil is one of the leading causes of drive belt damage so immediate replacement is advised.

Loose belts are also a problem. Most cars today are equipped with a belt tensioner that works automatically to ensure that the belt is always properly adjusted, but some still require manual adjustment. A rattling sound can be an indication that your drive belt tensioner is faulty.

What causes drive belt wear?

One of the most common causes of excessive and premature belt wear is a misaligned alternator. When the alternator is misaligned, so is the pulley that moves the belt. Another cause is a missing or damaged engine under shield, this is what protects the belt from water, dirt, small rocks, and other compounds that can cause it to wear more quickly. Oil or coolant leaks and improper tension can also cause wear.

Don’t take chances

Don’t neglect your drive belt. The last thing you want is to end up roadside with an overheated, badly damaged engine because your water pump or cooling system failed, or to lose your power steering on a tight curve. Don’t risk damage to your car’s engine, or to yourself.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...
Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...


Related questions

Q: Alternator belt got torn whilst driving and had new belt fixed but the car won't move on drive or reverse after few seconds drive

This is a sign of a faulty transmission control solenoid. Modern automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car's computer activates a transmission solenoid, which directs transmission fluid into the...

Q: Chirping sound coming from car

You're probably right. that sounds like it might be a belt slipping when you accelerate. If the belt(s) have never been replaced than they are certainly due, and at the age of your car its probably ready for a new...

Q: Hi, i have a 09 VW GTI, 4 WD and engine 2.0L. VW dealer inspected the car and advised to replace the upper and lower timing cover,

Hello. A timing belt cover replacement on your particular vehicle is a moderately intrusive job, but it can be done at your home or a place of your choice. Replacing the cover takes about 3 hours because the crankshaft must...